fix: converge workbench session state projection

internal/cloud/server-code-agent-http.ts

@@ -162,6 +162,10 @@ export async function handleCodeAgentSessionsHttp(request, response, url, option
     await getManualCodeAgentSession(response, options, sessionId);
     return;
   }
+  if (request.method === "DELETE" && sessionId && !action) {
+    await archiveManualCodeAgentSession(response, options, sessionId);
+    return;
+  }
   if (request.method === "POST" && sessionId && action === "select") {
     await selectManualCodeAgentSession(request, response, options, sessionId);
     return;
@@ -249,6 +253,31 @@ async function getManualCodeAgentSession(response, options, sessionId) {
   });
 }
 
+async function archiveManualCodeAgentSession(response, options, sessionId) {
+  const session = await getVisibleManualAgentSession(options, sessionId);
+  if (!session) {
+    sendJson(response, 404, manualSessionErrorPayload({ code: "session_not_found", message: "Code Agent session is not visible to the current actor.", sessionId }));
+    return;
+  }
+  const result = await options.accessController?.store?.archiveAgentConversation?.({
+    ownerUserId: options.actor?.id,
+    actorRole: options.actor?.role,
+    ownerScoped: true,
+    sessionId,
+    conversationId: session.conversationId,
+    projectId: session.projectId
+  }) ?? { count: 0 };
+  sendJson(response, 200, {
+    ok: true,
+    status: "archived",
+    contractVersion: "code-agent-manual-session-v1",
+    archivedCount: result.count ?? 0,
+    session: publicManualAgentSession({ ...session, status: "archived", endedAt: session.endedAt ?? new Date().toISOString(), updatedAt: new Date().toISOString() }),
+    valuesRedacted: true,
+    secretMaterialStored: false
+  });
+}
+
 async function selectManualCodeAgentSession(request, response, options, sessionId) {
   const body = await readJsonObjectBody(request, options.bodyLimitBytes);
   if (!body.ok) {